The present invention pertains to screen printing machines for simultaneously performing multiple printing operations in a continuous manner.
The printing of shirts, jerseys and the like has been, in large part, a labor-intensive operation in which most of the printing steps are performed manually by an operator. This system not only generates high production costs, but also a low output of finished goods, since the operators generally only work one article at a time.
In an effort to alleviate these difficulties, past artisans have fabricated printing machines capable of simultaneously performing multiple printing operations at a number of adjacent stations. Examples of such machines are illustrated in: U.S. Pat. No. Re. 29,160 issued Mar. 29, 1977 to Jaffa, and entitled SCREEN PRINTING MACHINE WITH OVAL RAIL FOR INDEXING PALLETS; and U.S. Pat. No. 4,407,195 issued Oct. 4, 1983 to Jaffa, and entitled SCREEN PRINTING MACHINE. However, while these machines do increase the efficiency of the printing operations, they are also very cumbersome and complex in nature.
More specifically, these machines are provided with a plurality of adjacent printing heads which are designed for pivotal movement between an operative position in which the screens engage the articles and an inoperative position in which the heads are disengaged therefrom. These printing heads are large and cumbersome mechanisms including: frames mounting screens; squeegee and flood bar assemblies; carriage and track means for movably supporting such assemblies; and drive means for operating the carriages, squeegees and flood bar assemblies. Large structural members and large lifting elements are required to facilitate the requisite pivoting operations thereof. Furthermore, this continual tipping of the screens makes effective management of the ink contained therein difficult. Consequently, the difficulty of continually achieving a uniform printing operation is compounded.
Since the printing heads are subjected to a fixed arcuate pivoting motion, the pallets supporting the articles must be accurately aligned beneath the screens to facilitate the desired printing operation. Alignment problems are particularly acute when the adjacent printing stations are utilized for the printing of different colors upon the same article to thereby form a multi-colored picture or pattern thereon. These prior art machines have fixedly mounted the supporting pallets onto the endless chain drives and have provided complex and costly precision mechanisms to control the drive means in an effort to ensure true alignment. However, despite these efforts, true and uniform alignment is not consistently possible due to the inherent variances incurred through the use of an endless chain drive.